2025 Nelsen Corporation Catalog - Catalog - Page 440
17 Feed Pump Sizing
Technical & Engineering
Polyphosphate Treatment For Water Systems
In order to size a feed pump for polyphosphate feeding it is
necessary to know:
It is advisable to slug the system initially at 10 ppm
for approximately 30 days to clean out the lines at a
faster rate.
a) the polyphosphate residual (ppm), and
Useful Data:
b) the well pump rate (gpm).
Polyphosphate @ 1 lb/10 gal = 12,000 ppm
Rule 1: One pound of polyphosphate per 10 gallons water =
12,000 ppm (solution strength)
5.25% bleach = 52,500 ppm
Rule 2: One pound of polyphosphate typically
treats 40,000 gallons of water at a 2 ppm
concentration (residual).
12.5% bleach = 125,000 ppm
Potassium Permanganate @ 0.25 lbs/gal = 30,000 ppm
• It requires 3 ppm chlorine for each ppm of
hydrogen sulfide.
Formula: [Well pump rate (gpm) x polyphosphate residual
(ppm) x 1440 (conversion factor)] ÷ solution strength
= required feed pump output (gpd)
• It requires 1 ppm chlorine for each ppm of iron.
Example:
• It requires 0.7 ppm potassium permanganate for each ppm
of hydrogen sulfide or iron.
Well pump rate = 10gpm
• Do not neglect the residual required for
chlorine applications.
Polyphosphate residual = 4 ppm
(10 x 4 x 1400) ÷ 12,000 =
• Do not mix potassium permanganate stronger
than 0.25 lbs/gal or the maximum solubility will
be exceeded.
56,000 ÷ 12,000 = 4.66
feed pump output (gpd), with 10 = well pump rate;
4 = the desired concentration of polyphosphate;
1440 = the conversion factor to change gpm to gpd;
12,000 = the solution strength based on the above Rule 1;
and 4.66 = the feed pump output (gpd) based on well pump
rate and polyphosphate residual.
Sizing Feed Pumps
In sizing feed pumps for iron and hydrogen sulfide removal using chlorine bleach or potassium permanganate,
the following formula can be used:
Well pump
flow rate
in gpm
x
Required
dosage
in ppm
x
Solution
(1440)
in ppm
÷
strength
=
Feed rate
required
in ppm
Size the chemical feed pump so that its maximum capacity is double the required feeding.
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